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NOTES ON MAASTRICHTIAN (CRETACEOUS) POLLEN IN THE SOUTH CAROLINA COASTAL PLAIN

By Raymond A. Christopher

U.S. Geological Survey Open-File Report 00-049-D
2000



INTRODUCTION


Owens and Gohn (1985), Owens (1989), and Sohl and Owens (1991), among others, interpreted the Upper Cretaceous Series of the Carolina Coastal Plain as consisting of rapidly changing lithofacies deposited in deltaic to open marine shelfal environments. These lithofacies changes occur along strike as well as in the dip direction, and proper interpretation of their spatial distribution requires an accurate and refined chrono- and biostratigraphic framework. Palynology, especially the study of terrestrially derived spores and pollen, is an essential component of such a framework, as these fossils are abundant, diverse, and most importantly, they provide a reliable basis for correlating marine and nonmarine facies.

A Cretaceous biostratigraphic zonation based on terrestrial palynomorphs was developed for the Carolinas in the early 1980s, but until recently (see Christopher and others, 1999 ), neither the details of the zonation nor the taxonomy of the palynomorphs upon which the zonation is based had been published. It is the intent of this report to present the palynological zonation applied to the Maastrichtian Stage of the Coastal Plain Province of the southeastern United States, and to discuss the morphology of the palynomorphs upon which these zones are based. It is important to note that this open-file report is not a valid publication medium for formally proposing new or revised paleontologic zonations or taxonomic information. For this reason, the palynologic zonation and the accompanying taxonomic comments provided herein cannot be considered as formally proposed or validly published.


PALYNOLOGICAL ZONATION OF THE MAASTRICHTIAN STAGE OF THE COASTAL PLAIN PROVINCE, SOUTHEASTERN UNITED STATES


Three interval biozones are recognized within the Maastrichtian Stage of the southeastern Coastal Plain that are based on the last appearance datums (LADs) of select pollen taxa. Each zone is described below, and included in the description is a definition of the zone, a discussion of its palynological characteristics, and a discussion of its observed distribution in the DOR-037 and DOR-211 wells. Morphological details of the stratigraphically important pollen types are presented in a subsequent section of this report.

Sparganiaceaepollenites sp. U Interval Biozone (Su Zone)


Definition. The Sparganiaceaepollenites sp. U Interval Biozone is defined as the stratigraphic interval between the last appearance datum of Sparganiaceaepollenites sp. U and the last Cretaceous appearance datum of Holkopollenites chemardensis Fairchild in Stover et al. 1966.

Palynological Characteristics. The Sparganiacaeapollenites sp. U zone is the youngest of the Cretaceous palynological zones, and the nominate taxon has been observed in all samples assigned to the zone from the Coastal Plain Province of South Carolina. Frederiksen (1980) reported a morphologically similar pollen type (Sparganiaceaepollenites sp.) as an "infrequent" element in a single sample from the early Sabinian (late Paleocene) of the Clubhouse Crossroads (DOR-037) core, but this occurrence may represent reworking from underlying Cretaceous units (Frederiksen, oral communication, 1999).

The LAD of Sparganiacaeapollenites sp. U is the palynological criterion that defines the top of the biozone, and because the Su zone is the youngest of the Cretaceous pollen zones, the highest in-place stratigraphic occurrence of this pollen type can also be used to recognize the Cretaceous-Tertiary boundary. However, the LADs of several additional pollen taxa also correspond to the top of the Cretaceous section in South Carolina, and can therefore be used to identify (or corroborate) the position of the Cretaceous-Tertiary boundary. Some of these taxa are restricted to the Su zone:

Striaperipollis gracillistriatus Krutzsch 1966. This species is typically a rare element in assemblages from the zone, but it is consistent in its occurrence within the Su zone. Striaperipollis gracillistriatus has been reported previously from the Santonian of southern France by Krutzsch (1966) and from the Santonian/Campanian of Portugal by Kedves and Hegedus (1972). It has not been reported previously from the Coastal Plain Province of the U.S., and in South Carolina, its stratigraphic distribution is restricted to the upper Maastrichtian.

Tricolpites microreticulatus Belsky, Boltenhagen and Potonie 1965. This species has been reported only from the Maastrichtian Stage in North America (Norton and Hall, 1969; Srivastava, 1969; Leffingwell, 1971; Farabee and Canright, 1986); however, Belsky et al. (1965) reported the species as occurring in the Senonian (Campanian or Santonian), and only possibly as occurring in the Maastrichtian of equatorial West Africa. In South Carolina, its LAD is coincident with the top of the Cretaceous section (i.e., coincident with the top of the Su zone), which is consistent with its other reported North American occurrences.

Libopollis jarzenii Farabee, Daghlian, Canright & Oftedahl 1984. This species is restricted to the Su zone in nine of the wells examined from South Carolina, but it has been observed in the upper part of the underlying Holkopollenites chemardensis Interval zone in one core from Orangeburg County, South Carolina (ORG-393). Although additional analyses are required to determine the precise relationship between the first appearance datum of Libopollis jarzenii and the Su zone, preliminary observations suggest that its FAD is more indicative of the Sparganiaceaepollenites sp. U zone than it is of any other biozone considered in this report.

Interpollis cf. I. supplingensis (Pflug in Thomson & Pflug 1953) Krutzsch 1960, of Tschudy, 1975 (= morphotype NH-1 of Wolfe, 1976). This taxon is very erratic in both its occurrence and its relative abundance. It has been observed in fewer than half the sections examined, but it appears to be restricted to the Su zone in South Carolina. Tschudy (1975) reported the species as occurring throughout the Maastrichtian of the Mississippi embayment, with rare occurrences in the Campanian and a questionable occurrence in the Paleocene. Wolfe (1976) reported the taxon (as morphotype NH-1) from the Monmouth Formation of Maryland, but did not observe it from correlative units in New Jersey.

Other taxa with LADs that correspond to the Cretaceous-Tertiary boundary have stratigraphic distributions that extend below the base of the Su zone; in addition to Sparganiaceaepollenites sp. U , these taxa are:

Rugubivesiculites spp. Representatives of this bisaccate pollen genus occur in all of the samples from the zones discussed in this report, and the genus ranges throughout the entire Upper Cretaceous Series of the Coastal Plain Province, where it is a common to frequent element, even in assemblages from open marine environments. In addition, Brenner (1963) reported the genus from the Patapsco Formation of Maryland, to which Doyle and Robbins (1979) assigned a middle Albian age.

Plicatopollis cretacea Frederiksen & Christopher 1978 (= morphotype NN-2 of Wolfe, 1976). The range of this taxon is restricted to the three zones discussed in this report. However, its presence and relative abundance is highly variable, and in some wells it has not been observed in any of the samples from these zones. Preliminary observations indicate that Plicaopollis cretacea may be more consistent in its presence and it may occur with a higher relative frequency in sections that are terrestrial or more near-shore in origin than those whose depositional environment reflects open marine conditions. Wolfe (1976) reported the taxon (as morphotype NN-2) from the Navesink and Red Bank Formations of New Jersey, and the Monmouth Formation of Maryland. Based on calcareous nannofossil data, Self-Trail and Bybell (1995) assigned a Maastrichtian Age to the Navesink Formation (calcareous nannofossils Subzones CC 26a, CC 25b, and CC 25a).

Longaevipollis sp. B (= morphotype MPH-2 of Wolfe, 1976). As with Plicatopollis cretacea, this morphotype is restricted to the three biozones discussed herein, but it is sporadic in its occurrence and variable with regard to its relative abundance. Wolfe (1976) reported Longaevipollis sp. B (as morphotype MPH-2) from the lower part of the Navesink Formation of New Jersey and the lower part of the Monmouth Formation of Maryland; these units are Maastrichtian in age.

The FAD of Equisetosporites volutus (Stanley) Farabee & Canright 1986 also occurs within the Sparganiaceaepollenites sp. U zone. Both Stanley (1965) and Farabee and Canright (1986) reported the FAD of the species from Maastrichtian units of the Western Interior, but Stanley (1965) reported the LAD of the species from Paleocene strata of South Dakota. Therefore, although the FAD of Equisetosporites volutus occurs within the Maastrichtian, it is known to range into the Tertiary, and its LAD cannot be used to identify the Cretaceous-Tertiary boundary.

The LAD of Trisectoris costatus Tschudy 1970 occurs toward the base of the Su zone. It is typically an infrequent element in assemblages, and it is rarely consistent throughout its stratigraphic range. Tschudy (1970) reported a single occurrence of the species from the Clayton Formation of early Paleocene age in the Mississippi embayment, but made no comment regarding the possibility that this specimen may be reworked. The range of the species extends downsection into the lower Campanian in both the Mississippi embayment region and in South Carolina.

Occurrence of the Zone in Dorchester County, South Carolina. The Sparganiaceaepollenites sp. U zone was recognized in the three highest samples examined from the Cretaceous section of the Clubhouse Crossroads core (DOR-037): 804, 830, and 850 feet (drill depth). In the St. George core (DOR-211), the zone occurred in only the highest of the two samples examined from the Cretaceous section, at 738 feet (drill depth).

Holkopollenites chemardensis Interval Biozone (Hc Zone)


Definition. The Holkopollenites chemardensis zone includes the strata between the last Cretaceous appearance datum of Holkopollenites chemardensis Fairchild in Stover et al. 1966 and the last appearance datum of Momipites sp. T .

Palynological Characteristics. The stratigraphic distribution of Holkopollenites chemardensis is unusual in that it occurs in the Tertiary (the type specimen is from the Paleocene Naborton Formation of Louisiana) and from Cretaceous units in the Atlantic Coastal Plain (Wolfe, 1976, as morphotype CP3D-3; Christopher, 1978). However, there is a very consistent and significant "gap" in its stratigraphic distribution that includes the upper part of the Maastrichtian Stage in the Carolinas. It should be noted that the morphology of H. chemardensis is highly variable in both its Cretaceous occurrences (personal observations by RAC) and in its Tertiary occurrences (N. O. Frederiksen, oral communication, 1999), and detailed studies of these Cretaceous and Tertiary specimens are warranted before it is concluded that the Cretaceous and Tertiary forms are or are not conspecific. Until such studies are completed, H. chemardensis should be regarded as a "Lazarus taxon" (Jablonski, 1986) whose highest Cretaceous occurrence in South Carolina is a useful biostratigraphic horizon.

Typically, the Hc zone is not as thick as the Su zone in South Carolina. For this reason, fewer samples have been examined from, and fewer biostratigraphic datums are associated with the Holkopollenites chemardensis zone than with the overlying zone.

The first appearance datum (FAD) of Sparganiaceaepollenites sp. U occurs in the upper part of the Holkopollenites chemardensis zone. Sparganiaceaepollenites sp. U is considerably less abundant in the Holkopollenites chemardensis zone than it is in the overlying zone, where its relative abundance generally ranges between 1 and 5 per cent of the entire assemblage (including marine palynomorphs).

In only one well thus far examined (SCDNR Testhole C-15, Jasper County, South Carolina) has the LAD of Plicapollis usitatus Tschudy 1975 been observed within the Hc zone. This occurrence may represent reworking from older parts of the section; however, the stratigraphic range of the species as reported by Tschudy (1975) and Wolfe (1976, as morphotype NE-3) suggest that the species occurs in units that are, based on calcareous nannofossil data, correlative with the Hc zone. The range of Plicapollis usitatus extends downsection into the lower Campanian.

Occurrence of the Zone in Dorchester County, South Carolina. The Hc zone has been identified in the Clubhouse Crossroads core (DOR-037) in the sample at 865 feet (drill depth), and in the St. George core (DOR-211) in the sample at 778 feet (drill depth).

Momipites sp. T Interval Biozone (Mt Zone)


Definition: The Momipites sp. T zone includes the strata between the last appearance datum of Momipites sp. T and the last appearance datum of Osculapollis aequalis Tschudy 1975.

Palynological Characteristics: The zone has been observed in numerous subsurface sections throughout South Carolina, but its thickness never exceeds 25 feet and it is possible that in some sections, the zone is not detected because of sample spacing. In several of the subsurface sections examined from South Carolina, the zone is represented by only a single sample.

Momipites sp. T is restricted to this zone, and it rarely constitutes more than 1 per cent of the assemblage. Although defined as an interval zone, the total range of Momipites sp. T also defines the zone. No LADs are considered biostratigraphically important within the zone, but the FADs of Plicatopollis cretacea and Longaevipollis sp. B coincide with the base of the zone.

Occurrence of the Zone in Dorchester County, South Carolina. Although the Mt zone has not been identified in either the Clubhouse Crossroads (DOR-037) or the St. George (DOR-211) cores , it is discussed herein because the zone constitutes a major biostratigraphic unit that is geographically widespread, has been recognized in sediments reflecting terrestrial to open marine environments, and contains a unique and distinctive pollen microflora that clearly differentiates it from adjacent zones. However, with regard to the Dorchester County wells, the LAD of Osculapollis aequalis, which defines the base of the Momipites sp. T zone, occurs in the Clubhouse Crossroads core (DOR-037) at 885 feet (drill depth), and although O. aequalis was not observed in the St. George core (DOR-211), the palynomorph assemblage at 794 feet (drill depth) suggests that the base of the Mt zone occurs at or above this depth. Therefore, the Mt zone, if present in these cores, occurs between 885 and 865 feet in the Clubhouse Crossroads core (DOR-037), and between 794 and 778 feet in the St. George core (DOR-211).


MORPHOLOGY OF STRATIGRAPHICALLY IMPORTANT POLLEN


Several of the stratigraphically important pollen types mentioned in this report have not been validly published, and for this reason, brief discussions of the morphological characteristics of the pollen types mentioned herein are presented, accompanied by photomicrographs. These discussions are designed to aid in the recognition of the palynomorphs, and do not constitute formal descriptions. The bar in each photomicrograph represents 10 mm.


Sparganiaceaepollenites sp. U


Diagnostic features. Spherical, reticulate, monoporate grains, diameter between 24 and 32 micrometers (average 30 micrometers). Exine <= 1.5 micrometers, 2-layered; inner layer smooth, apparently unstructured, uniform in thickness and appearance across the grain, and considerably thinner than the outer layer; outer layer consists of duplicolumellate (occasionaly simplicolumellate) muri that measure 1 to 1.3 micrometers in width and in height. Lumina of reticulum rounded-polygonal and equant in shape, rarely elongated, with diameters that vary between 1 and 2 micrometers, but tending toward the larger size. Pore circular, 4 to 7 micrometers in diameter, unbordered, with irregular margins; irregularity of the pore margins is enhanced by lumina that open directly into the pore (i.e., muri are absent on the side of the lumina that border the pore).

Sparganiaceaepollenites sp. U


Striaperipollis gracillistriatus Krutzsch 1966


1966 Striaperipollis gracillistriatus Krutzsch, Geologie, Beiheft 55, p. 22, pl. 1, figs. 4-6.

1972 Striaperipollis gracillistriatus W. Kr. 1966 em, Kedves and Hegedus, Bot. Kozlem., vol. 59, no. 1, p. 19 and p. 21, figs. 10-18.

Diagnostic features. Spherical, pantoporate grains with 5, 6, or 7 pores per hemisphere. Overall diameter between 20 and 29
micrometers (average 23.5 micrometers). Exine 2-layered; inner layer unstructured, uniformly 0.5 micrometers thick; outer layer 0.75 to 1 micrometers thick, tectate, with delicate and closely spaced columellae. Outer and inner wall layers are appressed in the vicinity of each pore, but are separated elsewhere; the region of appressed wall layers is centered about each pore, and has a circular shape with a radius of 2 to 5 micrometers; elsewhere, the outer and inner wall layers are separated by as much as 7 micrometers, but more typically by 3 to 5 micrometers; whereas the inner wall defines a spherical to slightly elongated inner body, the outer wall is undulatory or "wavy." The circular region of appressed wall layers surrounded by an area where the wall layers are separated creates a series of cup- or bowl-shaped structure with a pore at the center of each cup; occasionally, the bowl-shaped region of appressed wall layers will incorporate 2 (rarely 3) pores. Pores lack annuli, and are circular to slightly oval in shape, 2 to 4 micrometers in diameter, and spaced 4 to 8 micrometers apart; some pores are covered with a granular operculum; in some cases, the operculum may be folded back from the pore but remain attached to the outer wall. Surface of the outer wall is ornamented with very faint and delicate striae.

Striaperipollis gracillistriatus


Tricolpites microreticulatus Belsky, Boltenhagen and Potonie 1965


1965 Tricolpites microreticulata Belsky, Boltenhagen and Potonie, Palaon. Zeitschr., vol 39, pt. 1/2, p. 75, pl. 12, figs. 8, 9.

1966 Tricolpites microreticulatus Belsky, Boltenhagen and Potonie, Srivastava, Pollen et Spores, vol. 8, no. 3, p. 548, pl. VII, figs. 24, 25.

1967 Tricolpites reticulatus Cookson ex Couper, Norton and Hall, Review of Palaeobotany and Palynology, vol. 2, p. 105-106, pl. 1, fig. E.

1969 Tricolpites reticulatus Cookson ex Couper, Norton and Hall, Palaeontographica, Abt B, p. 43-44, pl. 7, fig. 1.

1969 Tricolpites reticulatus Cookson 1947, Oltz, Palaeontographica, Abt B, vol. 128, p. 141-142, pl. 41, fig. 103.

1971 Gunnera microreticulata (Belsky, Boltenhagen and Potonie, 1965) n. comb., Leffingwell, Geological Society of America Special Paper 127, p. 37, pl. 6, figs. 7, 8.

1986 Tricolpites microreticulatus Belsky, Boltenhagen and Potonie 1965, Farabee and Canright, Palaeontographica, Abt B, vol. 199, p. 67, pl. 23, figs. 9-13.

Diagnostic Features. Oblate-spheroidal shape; microreticulate sculpture; planaperturate and somewhat gaping colpi. Some grains exhibit a slight exinal thickening in the polar regions. Equatorial diameter 22 to 29
micrometers.

Comments. Very rare specimens of Tricolpites reticulatus Cookson 1947 ex Couper 1953 co-occur with T. microreticulatus in some samples from the Sparganiaceaepollenites sp. U zone. The coarser reticulum and slightly thicker exine of T. reticulatus differentiate it from T. microreticulatus.

Tricolpites microreticulatus


Libopollis jarzenii Farabee, Daghlian, Canright & Oftedahl 1984


1984 Libopollis jarzenii Farabee, Daghlian, Canright & Oftedahl, Palynology, vol. 8, p. 152-156, pl. 1, figs. 1-14; pl. 2, figs. 1-9; pl. 3, figs. 1-5.

1986 Libopollis jarzenii Farabee, Daghlian, Canright & Oftedahl, Farabee and Canright, Palaeontographica, Abt B, vol. 199, p. 73, pl. 26, figs. 1-12.

Diagnostic Features. Oblate-spheroidal shape, hexaporotricolpate apertures with the pores situated at the polar ends of the colpi and with colpi that narrow toward the equator; margo of uniform width and height surround colpi; reticulate surface with the height of the muri uniform around the entire grain and lumina that are polygonal and equant; equatorial diameter 17 to 37
micrometers.

Libopollis jarzenii


Interpollis cf. I. supplingensis (Pflug in Thomson & Pflug 1953) Krutzsch 1960, of Tschudy, 1975


1975 Interpollis cf. I. supplingensis (Pf.) Krutzsch 1960b, Tschudy, U.S. Geological Survey Professional Paper 865, p. 11-12, pl. 4, figs. 1-21; text-fig. 6.

Diagnostic Features. Oblate shape with a subcircular to subtriangular subequatorial outline; exogerminals hexaporate with pores paired, subequatorial, and angulaperturate; endogerminals triporate and equatorially situated; some grains with an equatorial constriction; with an exinal polar thinning; surface smooth; subequatorial diameter 18 to 25
micrometers.

Interpollis cf. I. supplingensis


Rugubivesiculites spp.


Diagnostic Features. Bisccate grains with a rugulate proximal cap.

Rugubivesiculites spp.


Plicatopollis cretacea Frederiksen & Christopher 1978


1978 Plicatopollis cretacea Frederiksen & Christopher, Palynology, vol. 2, p. 135, pl. 2, figs. 17-22.

Diagnostic Features. Oblate shape with a triangular equatorial outline, nonprotruding apertures, and straight to slightly convex sides; exogerminals without annuli or annuli weakly developed, and with faint radially directed baculae; triradiate thickening of inner wall (endoplicae) centered over each pole and radiating toward the germinals; thickening not accompanied by an adjacent area of exinal thinning; diameter 21 to 28
micrometers.

Plicatopollis cretacea


Longaevipollis sp. B


Diagnostic Features. Oblate shape, stephanocolpate (very rarely stephanocolporate), with a circular equatorial outline that is invaginated in the coplate regions; exine 2-layered; inner layer 0.25 to 0.5
micrometers, uniform around entire grain; outer layer consisting of baculae that measure 0.25 micrometers in both diameter and height, and which are spaced 0.5 to 1 micrometers apart; baculae support a tectum perforatum that is 0.25 micrometers thick; colpi short, extending poleward 1/4 to 1/3 the radius of the grain; colpi are not gaping and are unbordered; colpi typically 5 in number, rarely 6; equatorial diameter 17 to 23 micrometers, with an average diameter of 20 micrometers.

Longaevipollis sp. B


Equisetosporites volutus (Stanley 1965) Farabee & Canright 1986


1965 Ephedra voluta Stanley, Bulletins of American Paleontology, vol. XLIX, no. 222, p. 284-285, pl. 40, figs. 10, 11.

1986, Equisetosporites volutus (Stanley) comb. nov., Farabee and Canright, Palaeontographica, Abt B, vol. 199, p. 32, pl. 9, fig. 7.

Diagnostic Features. Muri (= ridges of Singh, 1964) do not coalesce or fuse at the longitudinal ends of the grain, but turn or curve back to form parallel sets; muri typically oriented at an angle to the long axis of the grain; short axis measures 18 to 22
micrometers, long axis measures 38 to 44 micrometers.

Equisetosporites volutus


Trisectoris costatus Tschudy 1970


1970 Trisectoris costatus Tschudy, U.S. Geological Survey Professional Paper 643-F, p. F8-F9, pl. 7, figs. 3-14.


Diagnostic Features. Syncolpate grains that generally occur as isolated thirds, with separation of the grain occurring along the germinals; isolated segments typically cup-shaped or curved the longitudinally; with longitudinally oriented muri or ribs supported by robust dulpicolumellae; muri adjacent to colpi are continuous around the polar area, whereas the muri not adjacent to colpi thin poleward and may merge or fuse in the polar regions; maximum width of muri is 2 to 4
micrometers; length of individual segments 24 to 32 micrometers, width of individual segments 25 to 30 micrometers.

Trisectoris costatus


Holkopollenites chemardensis Fairchild in Stover, Elsik & Fairchild 1966


1966 Holkopollenites chemardensis Fairchild n. sp., Stover, Elsik and Fairchild, The University of Kansas Paleontological Contributions Paper 5, p. 6, pl. 2, figs. 8a-c, 9a, b.

Diagnostic Features. Tricolporate, oblate to suboblate shape; polar regions are usually flattened, and the equatorial outline is triangular with straight to very slightly concave sides; the inner surface of the inner wall layer is incised with channels that are variable in width (0.5 to 4
micrometers) and number (4 to 8), and which are oriented parallel to the sides of the grain when viewed in polar orientation; secondary channels may connect those that parallel the sides of the grain; equatorial diameter of grains 28 to 38 micrometers.

Comments. As discussed by Christopher (1981), a number of Upper Cretaceous pollen types in addition to Holkopollenites chemardensis exhibit channeling of the inner wall layer, but which vary with regard to size, shape, orientation of the channeling, surface ornamentation, and wall thickness. The large size, triangular equatorial outline, and parallel channeling of the inner wall layer are the primary characteristics that differentiate H. chemardensis from other pollen types.

Holkopollenites chemardensis


Plicapollis usitatus Tschudy 1975


1975 Plicapollis usitatus Tschudy, U.S. Geological Survey Professional Paper 865, p. 17-18, pl. 9, figs. 6-14, text-fig. 13.

Diagnostic Features. Oblate with a triangular equatorial outline in which the corners are rounded rather than blunt and the germinals tend to protrude from the outline; germinal region tends to be radially elongated; surface smooth; grains are small, with an equatorial diameter less than 23
micrometers (i.e., smaller than other Cretaceous species of the genus that occur in Coastal Plain sediments).

Plicapollis usitatus


Momipites sp. T


Diagnostic Features. Triporate, oblate grains with a triangular equatorial outline and straight to slightly concave sides; exine 2-layered; inner layer < 0.5
micrometers thick and forms a triangular "inner contour" with straight sides; outer layer 1 micrometers thick at the equatorial interapertural regions, and gradually thickens and flares outward in the direction of the apertures so that the outer contour is triangular with concave sides; thickening and flaring of the outer wall is more severe in the apertural area, where annuli are developed that exhibit very fine radially directed baculae on their inner surface; exoapertures are 1 micrometers wide and 2 micrometers long; endoapertures are simple (i.e., without structure), equatorially elongated, and tighly appressed against the exoaperture so that no vestibulum is present, or the vestibulum is very narrow and reduced; surface smooth; exine with a triangular thinned area centered over the poles with the apices oriented in the direction of the apertures; equatorial diameter 16 to 22 micrometers (average 18 micrometers).

Momipites sp. T


Osculapollis aequalis Tschudy 1975


1975 Osculapollis aequalis Tschudy, U.S. Geological Survey Professional Paper 865, p. 29, pl. 18, figs. 10-20; text-fig. 33.

Diagnostic Features. Oblate grains with a concavely triangular equatorial outline and broadly rounded to blunted apices; well developed annuli surround circular exoapertures that are located at the apices; annuli are formed by robust baculae that project radially inward from the inner surface of the outer wall; exine consists of 2 wall layers of equal thickness (1 to 1.5
micrometers thick) separated by an interloculum 1 micrometer wide; interloculum without columellae; equatorial diameter 19 to 23 micrometers.

Osculapollis aequalis


REFERENCES

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Brenner, G. J., 1963, The spores and pollen of the Potomac Group of Maryland: Maryland Department of Geology, Mines and Water Resources, Bulletin 27, 211 p.

Christopher, R. A., 1979, Quantitative palynologic correlation of three Campanian and Maestrichtian sections (Upper Cretaceous) from the Atlantic Coastal Plain: Palynology, vol. 2, p. 1-27.

Christopher, R. A., 1982, Holkopollenites pollen `lineage' from the Upper Cretaceous Series of the Atlantic and eastern Gulf Coastal Plain Province (abs.): Palynology, vol. 6, p. 274.

Christopher, R. A., Self-Trail, J. M., Prowell, D. C. and Gohn, G. S., 1999, The stratigraphic importance of the Late Cretaceous pollen genus Sohlipollis gen. nov. in the Coastal Plain Province: South Carolina Geology, vol. 41, p. 27-44.

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Open-File Report 00-049
Eastern Region Earth Surface Processes Team

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